Recently, as this kind of a light irradiation device for production inspection, an LED of a super high-intensity type referred to as a power LED is used as a light source. With this power LED, it is possible to obtain sufficient illumination intensity with a single power LED without using multiple LEDs and to simplify optical systems compared with a case of using multiple LEDs, thereby to simplify a structure of the light irradiation device.
As the light irradiation device using the power LED, the applicant of the present claimed invention has invented the light irradiation device shown in the patent document 1.
The light irradiation device has an arrangement wherein a housing can be separated into a rear side housing element of a cupped shape and a front side housing element, the rear side housing element and the front side housing element are threadably connected each other with their axial lines aligned with each other, an LED and an optical system accommodated inside of the housing elements are pressed between the front and the back through an elastic member such as an O-ring with an axial line of the LED aligned with an axial line of the optical system in a process of coupling the rear and front side housing elements. Then the light irradiation device is innovative because it can be assembled with high accuracy of position easily and heat also can be effectively dissipated with an arrangement wherein the housing is tightly attached to the LED.
Patent document 1: Japan patent laid-open number 2004-111377